To me Ben Mclemore has better upside as Shabazz doesn't contribute much at all on defense and isn't as good of a shooter as Mclemore. Mclemore is more athletic and is averaging a steal and a block per game and is a much better passer than Bazz. But where Mclemore has athleticism Bazz has length, up in the 7ft wingspan range. Also they have two different play styles. Ben works extremely well of the ball and fits better into the Bobcats offense because he doesn't need the ball. Bazz is better in iso situations and can spot up along with being able to drive better and post up as well. All around more versatile on offense at this point in their careers. Keep in mind too that Shabazz is in a more open offensive system at UCLA and Mclemore is in Bill Self's more organized system in Kansas. We'd have to see Mclemore given more freedom before you come to a conclusion about his ability to create offense.
However at this moment from what I have been able to see he doesn't show great talent at being able to create for himself but with his athleticism and shooting stroke i don't see that being much of an issue moving forward especially if he works on his ball handling. Shabazz does have that killer instinct that you like to see from big time players but he's not good with his off hand and his jumper still needs work but he's not far off. Both are good picks but I think Mclemore is more well rounded overall as a player but Shabazz is clearly better on offense mainly because of his better handling and driving ability.
Bennett is a SF and we have MKG and Taylor already. Getting him would be redundant and a wasted pick with Hendo possibly walking and Gordon on the trading block leaving a gaping hole at the 2.